Magnetic tapes are used as recording media for backup of computer data. Among magnetic tapes are ones which are configured in such a manner that a primer layer and a magnetic layer are laid on a base film and a back coat layer is formed on the surface, opposite to the surface on which the magnetic layer is formed, of the base film.
A magnetic tape is used being housed in a magnetic tape cartridge. For example, the magnetic tape cartridge is composed of a tape reel around which the magnetic tape is wound and a cartridge body which houses the tape reel.
In assembling a magnetic tape cartridge, a magnetic tape raw roll which has been manufactured in advance is slit into magnetic tapes and each of those magnetic tapes is wound up around the tape reel of a magnetic tape cartridge by a winding-up apparatus.
When a magnetic tape has been wound up around a tape reel by the winding-up apparatus, an air layer (what is called an air film) may be formed between adjoining turns of the wound-up magnetic tape. An air layer is formed through mixing of air that exists in the vicinity of a running portion of a magnetic tape being wound. If air layers are formed, the tightness of winding of a wound-up magnetic tape may be reduced when the tension that has been exerted on the magnetic tape during the winding is released after the completion of wounding-up around the tape reel. In such an event, after the magnetic tape cartridge is inserted into a drive device, an error may occur in a loading operation of pulling the magnetic tape into the drive device out of the magnetic tape cartridge or a magnetic recording or reproducing operation of the drive device.
In the winding-up apparatus disclosed in JP-A-2004-307091, when a magnetic tape is wound, the surface of a winding subject portion of the magnetic tape is pressed inward against a tape reel by a pressing mechanism to prevent inclusion of air through association with a running portion of the magnetic tape.